The present invention relates to guide bar adjustment mechanisms for chainsaws, and more particularly to an adjustment mechanism having a breakaway adjustment pin.
Various mechanisms are known for adjusting the tension of the chain on a chainsaw. Nearly all of these mechanisms involve the movement of the guide bar upon which the chain rests. By lengthening the guide bar, the chain tension is increased. Conversely, shortening the guide bar decreases the chain tension.
A commonly used mechanism for adjusting the position of the guide bar consists of an adjustment pin threaded onto an adjustment screw provided on the body of the chainsaw. The adjustment pin engages a hole in the guide bar. As the adjustment screw is rotated, the pin advances or retreats along the screw, moving the guide bar with it.
One problem with these adjustment pin type chain tensioning mechanisms occurs during assembly of the guide bar onto the chainsaw body. The pin is not normally visible once the bar is placed onto the body. If the guide bar and the adjustment pin are not properly aligned during assembly, the adjustment pin and/or adjustment screw can be damaged.